Document FR-A-1 138 752 describes an example of such a transmission system.
In the system described in that document, the radial deformation of the core disk under the effect of the high temperatures reached by said core disk while the retarder is in operation is accommodated solely by deformation of the arms for fixing the wheels of the rotor, with the inside ends of said fixing arms being rigidly united by an undeformable hub.
Consequently, the fixing arms are either complex in shape and therefore difficult to make, thus increasing the cost of the electrical retarder, or else simple in shape and poor at accommodating radial deformation, thereby increasing the mechanical stresses in the rotor and thus reducing its lifetime.